Revert "Add flowing water differentiation"

This reverts commit 00e89a514a.

layers/water/mapping.yaml

@@ -104,9 +104,4 @@ tables:
       - dock
       water:
       - river
-      - stream
-      - canal
-      - ditch
-      - drain
-      - lake
     type: polygon

layers/water/water.sql

@@ -1,7 +1,6 @@
 CREATE OR REPLACE FUNCTION water_class(waterway text, water text, leisure text) RETURNS text AS
 $$
 SELECT CASE
-           WHEN water IN ('river', 'canal', 'stream', 'ditch', 'drain') THEN 'river'
            %%FIELD_MAPPING: class %%
            ELSE 'lake'
            END;

layers/water/water.yaml

@@ -25,11 +25,7 @@ layer:
     class:
       description: |
           All water polygons from [OpenStreetMapData](http://osmdata.openstreetmap.de/) have the class `ocean`.
-          The water-covered areas of flowing water bodies with the [`water=river`](http://wiki.openstreetmap.org/wiki/Tag:water=river), 
-          [`water=canal`](http://wiki.openstreetmap.org/wiki/Tag:water=canal),
-          [`water=stream`](http://wiki.openstreetmap.org/wiki/Tag:water=stream),
-          [`water=ditch`](http://wiki.openstreetmap.org/wiki/Tag:water=ditch), or
-          [`water=drain`](http://wiki.openstreetmap.org/wiki/Tag:water=drain) tags are classified as river.  Wet and dry docks
+          Water bodies with the [`water=river`](http://wiki.openstreetmap.org/wiki/Tag:water=river) tag are classified as river.  Wet and dry docks
           tagged [`waterway=dock`](http://wiki.openstreetmap.org/wiki/Tag:waterway=dock) are classified as a `dock`.
           Various minor waterbodies are classified as a `pond`.
           Swimming pools tagged [`leisure=swimming_pool`](https://wiki.openstreetmap.org/wiki/Tag:leisure=swimming_pool) are classified as a `swimming_pool`
@@ -38,7 +34,7 @@ layer:
         dock:
           waterway: 'dock'
         river:
-          water: ['river', 'stream', 'canal', 'ditch', 'drain']
+          water: 'river'
         pond:
           water: ['pond', 'basin', 'wastewater']
         lake: